Offshore 27 Re-power with Twin Yamaha F300 4.2L
Posted: Wed Nov 11, 2015 1:28 pm
This is a first report of a test run [of a Boston Whaer OFFSHORE 27] with my recent engine replacement [of twin Yamaha F300 4.2-liter engines], but not many details for now as this was more of a shakedown trip.
The [Boston Whaler OFFSHORE 27] hull has two fresh coats of Micron 66 bottom paint, 243-gallons of fuel, the usual gear on board, and three people. I intended for my crew to take notes, however that assignment sort of faded away above 42-MPH.
[The Boston Whaler OFFSHORE 27] boat jumps on plane, and at 6,000-RPM we observed 57-MPH. The jack plates were at 50-percent and engine trim at 50-percent. The engine speed was still climbing, and, at this point, I backed off. Performance is beyond what I expected. Cruise will wind up around 3,500 to 4500-RPM, I think.
The propellers are Yamaha 19T from my old 1992 250-HP engines with carburetors, which were removed. Next I will try a pair of Yamaha SWS II 15x21 propellers.
I have added the extra battery charging leads to each engine and added water pressure senders. We put in new Seastar steering cylinders, as well. The electronic engine controls are great. I did not think they would be this nice. The engines are quiet and I can not tell if they are running from the helm at idle. Push button starts and stops are new to me also. We also took the opportunity to replace the electronics: Furuno and Sitex--out; Garmin--in. Also totally re-built the triple-axle trailer, adding electric-over-hydraulic disc brakes. [To discuss this topic, see the thread in REPAIRS and MODIFICATIONS--jimh]
Back at the dock you had to chisel the smiles from our faces. Real stats to come.
I saw on the Yamaha color display [indicating] 1.7-MPG at 50-MPH, but I have not yet set up the display, so I don't know what it was reading. Initially I had trouble seeing the engines on my Garmin chart plotters, but that was corrected back at the dock and was a simple menu setup item I missed.
--Chuck
The [Boston Whaler OFFSHORE 27] hull has two fresh coats of Micron 66 bottom paint, 243-gallons of fuel, the usual gear on board, and three people. I intended for my crew to take notes, however that assignment sort of faded away above 42-MPH.
[The Boston Whaler OFFSHORE 27] boat jumps on plane, and at 6,000-RPM we observed 57-MPH. The jack plates were at 50-percent and engine trim at 50-percent. The engine speed was still climbing, and, at this point, I backed off. Performance is beyond what I expected. Cruise will wind up around 3,500 to 4500-RPM, I think.
The propellers are Yamaha 19T from my old 1992 250-HP engines with carburetors, which were removed. Next I will try a pair of Yamaha SWS II 15x21 propellers.
I have added the extra battery charging leads to each engine and added water pressure senders. We put in new Seastar steering cylinders, as well. The electronic engine controls are great. I did not think they would be this nice. The engines are quiet and I can not tell if they are running from the helm at idle. Push button starts and stops are new to me also. We also took the opportunity to replace the electronics: Furuno and Sitex--out; Garmin--in. Also totally re-built the triple-axle trailer, adding electric-over-hydraulic disc brakes. [To discuss this topic, see the thread in REPAIRS and MODIFICATIONS--jimh]
Back at the dock you had to chisel the smiles from our faces. Real stats to come.
I saw on the Yamaha color display [indicating] 1.7-MPG at 50-MPH, but I have not yet set up the display, so I don't know what it was reading. Initially I had trouble seeing the engines on my Garmin chart plotters, but that was corrected back at the dock and was a simple menu setup item I missed.
--Chuck